This invention relates generally to tufted carpeting, and more particularly to tufted carpeting having an improved primary backing which includes two or three backing components or layers. This primary backing construction provides dimensional stability to the carpet without the necessity for a secondary backing.
In the past, tufted carpeting was made by tufting yarn into a backing of woven jute or the like. Because the jute backing was heavy and stable, it was coated on the back with latex or another adhesive to lock in the tufts, and the carpet was ready to install. More recently, however, various light weight materials have been used as a primary backing through which yarn is tufted, and a secondary backing of a heavier or more stable material is adhered to the back of the primary backing by an adhesive.
Currently, the most popular primary backings are made of polypropylene materials, either woven or non-woven. Such backings are preferred because they are inexpensive, and the material has an oily quality that provides for smooth entry and exit of the tufting needles. In addition, the material is quite elastic so the hole tends to close around the yarn after the tufting needle is withdrawn. However, the polypropylene backings have some disadvantages as well. Polypropylene is a thermoplastic elastomer, so the backing is subject to degradation by excess heat and is rather easily stretched through the application of tension.
Typically, after face yarns are tufted into a primary backing, the unfinished carpet is back coated with an adhesive to lock in the stitches. Without the back coating, the tufts are very easy to pull out, so the back coating is an important finishing step. During the coating process, however, the carpet is dimensionally unstable because of the presence of only the light-weight primary backing. Consequently, it is not uncommon to have elongation in the carpet in the range of 5%-20% during the back coating process. While this elongation may appear to xe2x80x9ccreatexe2x80x9d more carpet, it does so by reducing the amount of face yarn per unit area, so the resulting carpet will not be as densely tufted. Another problem with elongation is that the backing may not stretch uniformly, with the result that any pattern in the carpet will be distorted. Efforts have been made to physically prevent elongation of the carpet, but such efforts require additional equipment, time and effort, and still do not entirely solve the basic problem of stretching of the primary backing.
It is known to make rugs and carpets having a plurality of backings. For example, U.S. Pat. No. 2,713,012 of Hartstein discloses a tufted rug having dual primary backings of cotton and jute or the like. The Hartstein reference does not contemplate back coating of the rug, and instead relies on the double backing to assist in holding in the tufts. Furthermore, the jute backing is heavy enough to stabilize the rug so that elongation is minimized. U.S. Pat. No. 4,426,415 of Avery discloses a carpet in the nature of artificial turf having a plurality of primary backings and a conventional back coating. These backings varying in fineness from the bottom to the top of the carpet. All of the Avery backings are of the same material, and polypropylene is specifically mentioned. Since the Avery reference contemplates back coating of the carpet, the problem of elongation of the carpet and the resulting distortion of any pattern will still be present, though perhaps to a lesser degree because of the greater strength inherent in multiple backings. U.S. Pat. No. 4,705,706 of Avery discloses a multiple-layer primary backing of nylon or the like. Face yarns of polyethylene are tufted through this backing and the back stitch is set by heat, rather than by a separately applied adhesive. The multiple layers of backing described in this patent allow sand to infiltrate when the carpet is used as outdoor turf.
It is also known, as described in U.S. Pat. No. 4,096,302 of Thibodeau et al., to provide a carpet backing comprising non-woven fiber material that is needle punched into plastic netting. The fiber material, comprised of nylon, rayon, or similar fibers having a fiber length of about one to six inches, is deposited on the plastic net with the fibers aligned in the weft direction. The fibers are then secured to the net by needle punching them through the net. The fibers may be deposited and punched through the net serially one side at a time, or they may be deposited on both sides of the net and simultaneously needle punched through both sides of the net with a double acting loom. After the backing has been formed in this manner, carpet yarn is tufted into the backing. The tufts are held in the backing primarily by the fibers, but a back coating of adhesive may also be applied to the tufted carpet.
It is also known to provide a backing system for carpet comprising a primary backing and a secondary backing, with a thin film of liquid-impervious thermoplastic material bonded either to the back of the primary backing or the back of the secondary backing. U.S. Pat. No. 5,612,113 describes such a backing system in which yarn is tufted into a conventional primary backing such as is generally comprised of polypropylene. A conventional secondary backing or foam cushion is thereafter bonded to the primary backing to lock in the back stitches, by application of latex or other adhesive. In addition, however, a thin liquid-impervious film is applied either to the back of the primary backing or to the back of the secondary backing by use of an adhesive.
My copending patent application entitled Dimensionally Stable Tufted Carpet, Ser. No. 08/840,395, now U.S. Pat. No. 5,962,101 , describes a tufted carpet having a double-layer primary backing, the first part of such backing being formed of a woven or non-woven material, preferably a conventional woven ribbon polypropylene, and the second part having warp yarns and fill yarns, with at least the warp yarns having greater strength and less stretchability than the first part of the primary backing. The face yarns are tufted through both parts of the double-layer backing, which secures the two parts together, with the second part forming the back side of the carpet. Because the second part of the backing is of an open weave material, at least some of the back stitches protrude from the back of the carpet, so that an applied adhesive can truly encapsulate such stitches for maximum strength.
With the dual-layer primary backing, it has been found that the tufts are held more securely, even without back coating of the carpet, so the carpet can be handled as necessary without fear of loss of any substantial amount of face yarns. During back coating or other processing of the carpet, the non-stretchable part of the backing in the carpet prevents elongation or other stretching of the carpet. However, further research conducted since the time of filing of our co-pending application described above has revealed that dimensional stability may be obtained regardless of which of the first or second backing layers forms a first side of the primary backing (on which the tufts of yarn form face yarns) or the opposite (or back) side of the primary backing (on which the back stitches are formed), provided that suitable materials are selected for use as the first and second backing layers. Other research has revealed that several other materials may be incorporated into the primary backing for further improvement in the dimensional stability and overall quality of the carpet.
Accordingly, the invention described and claimed herein provides among its advantages greater dimensional stability in tufted carpet than has been previously available. Another advantage of the invention is that the quality of the carpet made according to the invention, including the integrity of the pattern and the density of face yarns per unit area is consistently high. Yet another advantage of an embodiment of the invention in which the first backing is comprised of a composite of a woven or non-woven material and a plastic sheet material, is a carpet with improved dimensional stability and moisture resistance. Still another advantage of an embodiment of the invention which includes a third layer in the primary backing is a carpet with even greater dimensional stability.
Additional advantages and features of this invention will become apparent from an examination of the drawings and the ensuing description.
As used herein, a plastic sheet material includes pliable sheets and films of any thickness that are comprised of any of various nonmetallic compounds that are synthetically produced, usually by polymerization, and which may be either thermosetting or thermoplastic. The term film is used synonymously with the term sheet herein.
As used herein, a composite of a woven or non-woven material and a plastic sheet material includes any of various combinations of woven or non-woven materials and a plastic sheet material. Such combinations include woven or non-woven materials to which a plastic sheet is bonded by use of an adhesive, by heat, or by extrusion of the plastic material thereon, as well as laminates and co-extrusions of such materials. A composite may also comprise a woven or a non-woven material and a plastic sheet material which are in intimate contact substantially across the area of the sheet material.
As used herein, particulate material includes powders and granules of various particle sizes.
As used herein, thermofusible particulate materials are those that may be deposited, dispensed or applied as particulate materials, which upon heating will coalesce and subsequently fuse together.
The invention comprises a tufted carpet having a primary backing comprised of at least two layers, including a first backing layer and a second backing layer. The first backing layer comprises a woven or a non-woven material, or a composite of a woven or non-woven material and a plastic sheet material. The second backing layer may comprise a woven material of ribbons of polypropylene, polyethylene or combinations of polypropylene and polyethylene. The second backing layer may also comprise a woven fiber glass material, a leno weave material, an open weave material, a plastic net or a plastic sheet material. A plurality of tufts of yarn are sewn through the primary backing, so that the tufts of yarn are exposed on one side of the primary backing for forming face yarns. The tufts of yarn also form a plurality of back stitches on the opposite side of the primary backing. At least a major portion of the back stitches secure each layer of the primary backing to each other layer. A method for making a tufted carpet having the characteristics set out above is also described and claimed herein.
In order to facilitate an understanding of the invention, the preferred embodiments of the invention are illustrated in the drawings, and a detailed description thereof follows. It is not intended, however, that the invention be limited to the particular embodiments described or to use in connection with the apparatus illustrated herein. Various modifications and alternative embodiments such as would ordinarily occur to one skilled in the art to which the invention relates are also contemplated and included within the scope of the invention described and claimed herein.